georefid:2007-026798SEDIS Publication Catalogue

ana.macario@awi.de

http://sedis.iodp.org/pub-catalogue/informationpointOfContact2011-06-23T00:00:00Zhttp://sedis.iodp.org/pub-catalogue/index.php?id=2007-0267981996-01-01publicationgeorefid:2007-026798issn:1058-1448Davis, EarlGeological Survey of Canada, Pacific Geoscience Centre, Sidney, BC, CanadaauthorFisher, AndrewUniversity of California at Santa Cruz, United StatesauthorFirth, JohnTexas A&M University, United StatesauthorOcean Drilling Program, Texas A&M University, College Station, TX, United StatespublisherdocumentDigitalScientific Prospectus16860 pp.1058-1448Simple examples of several common hydrothermal flow regimes have been found on the eastern flank of the Juan de Fuca Ridge. Ocean Drilling Program Leg 168 will focus on two of these, at sites where (1) there is a sharp transition from sediment-free to sediment-covered igneous crust, where heat flow, crustal temperatures, basement fluid compositions, and upper crustal seismic velocities all show large systematic changes associated with the transition from open to closed hydrothermal circulation, and where (2) buoyancy-driven fluid flow within the igneous crust and through the seafloor is strongly influenced by basement relief and sediment-thickness variations. If time permits, a third site may be studied where particularly flat basement and regionally continuous sediment cover should prevent advective heat loss and allow the total heat flow from this young lithosphere to be determined confidently. All of these examples represent situations that occur commonly in all ocean basins, but because of the unusual simplicity of the occurrences in this area, they provide ideal targets for drilling. Sampling, downhole measurements, and post-drilling observations will be directed mainly toward elucidating the physics and fluid chemistry of ridge-flank hydrothermal circulation, and the consequent alteration of the upper igneous crust and sediments that host the flow. Two arrays of relatively shallow holes will provide direct information about lateral gradients in basement fluid composition, formation pressures, and temperatures and strong constraints on formation-scale heat-transport properties of the upper igneous crust and the vigor of circulation.completedOceanographySolid-earth geophysicsbasementcirculationcrustEast Pacifichydrothermal conditionshydrothermal ventsigneous rocksJuan de Fuca RidgeLeg 168lithospheremarine sedimentsmid-ocean ridgesNorth PacificNortheast PacificOcean Drilling Programocean floorsoceanic crustoceanic lithospherePacific Oceansea watersedimentsthicknessurn:org.iodp:exp:168urnlargerWorkCitationcampaignEnglishgeoscientificInformation-129.0000-127.300047.450048.0000The reports in this series become obsolete after a cruise sails and will not be distributedapplication/pdfunknownSEDIS Publication Catalogue

ana.macario@awi.de

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